| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of the charging performance due to toner mixture in a charging device and a defective image by setting the image forming condition or prohibiting the image forming operation depending on the toner amount in a magnetic brush of the charging device. SOLUTION: A detecting device 24 to detect the DC current value flowing in a magnetic brush is arranged between a charging bias power source S1 and a magnetic brush charging device 2. The toner amount in the magnetic brush charging device is calculated and estimated by collating the measured current with the relationship between the toner amount in the magnetic brush charging device and the current quantity which are measured with the same potential in advance. An operation device 6 determines the process condition such as appropriate charging bias, developing bias or body operation by the toner amount, and the respective process conditions are thereby changed. When the toner of the prescribed amount is mixed in the magnetic brush charging device 2, the image forming operation of the body is prohibited, and setting is made so that the signal to give an alarm to a user is transmitted. |
